> codepath used in the wild: preapproval for a large file upload There is no current browser, or client that by default will send an Expect: 100-Continue. cUR

> codepath used in the wild: preapproval for a large file upload There is no current browser, or client that by default will send an Expect: 100-Continue. cURL removed it because it was too often broken. See https://curl.se/mail/lib-2017-07/0013.html https://curl.se/mail/lib-2017-07/0013.html As of right now, while server authors will continue to need to support it, it is unlikely that it is a well tested code path, and it will likely break in weird ways even trying to use it. So pre-approval for a large file upload is not even valid anymore.